1. Field of the Invention
The present invention relates to a light transmission type powder and granular material measuring apparatus and more particularly to a modular system that can be added as a measuring line to a continuous production line.
2. Description of Related Art
Light transmission powder and granular material measuring apparatus in which the powder and granular materials flow through a cell equipped with a glass window on both sides to be irradiated with a laser beam, e.g., through one glass window and with the light transmitted to the other glass window to be detected are well known. Based on the characteristics of the laser beam transmittance, the concentration and particle size distribution of the powder and granular material can be determined. However, any powder and granular material adhering to the cell window can lower the light transmittance and can affect the measurement of powder and granular material.
Therefore, in order to correctly measure an altered value due to the cloudiness of the glass window, light transmittance was measured when powder and granular material was not permitted to flow in the cell (blank or reference measurement), and with this blank measurement designated as a blank value, the blank value was subtracted from the actual measured value when the powder and granular material was allowed to flow. Therefore, the lowering of the measured value due to any cloudiness of the glass window was corrected and error was reduced.
However, in the above-mentioned light transmission powder and granular material measuring apparatus, the flow of the powder and granular material along a production line conduit to which the cell was connected must be stopped temporarily in order to carry out a blank measurement. Consequently, when the concentration and particle size distribution of powder and granular material flowing in the plant line was measured by a light transmission type powder and granular material measuring apparatus as described above, the line of the plant must be temporarily stopped during the blank measurement every time the blank measurement was carried out, and it has been generally unable to use such a light transmission type powder and granular material measuring apparatus as described above, in those plants where the line must be constantly operated.
Constantly, hitherto, a light transmission type powder and granular material measuring apparatus was generally not used for measuring the blank valve in a plant line, and in many cases, supervisors of plant lines had to control the product quality by their own experience accumulated over many years.